The current Apple TV is, in many respects, unbelievably bad, and it has nothing to do with the CPU.
Open up the YouTube app and try to navigate the UI. It’s okay but not really up to the Apple standard. Now try to enter text in the search bar. A nearby iPhone will helpfully offer to let you use it like a keyboard. You get a text field, and you can type, and keystrokes are slowly and not entirely reliably propagated to the TV, but text does not stay in sync. And after a few seconds, in the middle of typing, the TV will decide you’re done typing and move focus to a search result, and the phone won’t notice, and it gets completely desynchronized.